View Full Version : Pumping from a lake. What size pump to use?

03-22-2007, 07:48 PM
Ok guys I have got a question here that I hope you can help me out here with a little info. I got a area that is 195'x34'x195x52. It's not quite square. I am wondering on what size pump do i need to get? I have done irrigation on city water supply before but not one from a lake. I have read that you design the system first and then get a pump to fit the amount of water I need to flow. So If I am wanting to flow say 12 GPM do I get a pump to flow just that amount or do I add over kill to it? I have also got a hill of about 9 feet that I will have to push the water up to also. If you need more info let me know cause any help is better than no help.

03-22-2007, 08:03 PM
Find your constraints first. Then work from there. How much power to you have? A standard 15 amp branch circuit probably won't allow you more than half-horsepower pumps.

Look at using a shallow-well jet pump. They prime easily, and give you more pressure than ordinary centrifugal pumps will.

Use a local pump supplier, if at all possible. You want a supplier that can quickly take care of a problem.

Filter the water on the suction side, to protect the pump, and again on the outlet side, to keep crud out of the system.

Use heads that give you lots of wiggle room. Hunter PGP's can be a lifesaver, as you can swap nozzles and match up zone and pump performance.

03-22-2007, 08:15 PM
Our standard pump set-up is a 1 1/2hp flowing 20-25gpm at 50psi.

03-23-2007, 07:38 PM
Power will not be a issue because I can pretty well run what ever I want to it. Will rainbird 5004 be a good sprinkler head to use too? Also I was going to use the rainbird flow control valves with this set up too. Will that cause me any problems?

03-23-2007, 11:19 PM
Rainbird 5004s would be okay. The lawn area isn't so large, so you can get by with smaller pumps. You'll have an easier time obtaining 3/4 or 1 HP pumps, than larger ones. Cheaper, too.

03-24-2007, 09:26 AM
My personal preference has always been for submersible pumps rather than jet pumps. I love not having to prime submersibles. With that being said, there are a few basic things to understand about submersible pumps. Submersible pumps 3/4 hp and up come in two parts. You have the actual pump which determines how much flow you get in GPM, and then theres the motor which drives the pump, measured in HP. The requirement of your irrigation system determines what size pump you get, ie. your zones use 15 gpm then you need a 15 gpm pump. The motor on the other hand is determined by the vertical height you need to pump the water above the water level. If you give those two figures to your pump supplier, the GPM you need and the vertical height between the highest point of your system and the lvl of the water, he will give you the correct pump.

With the price of copper lately there are a few things you can do to keep your cost as low as possible. Submerisble pumps require two relays (provided you are not using a pressure tank). The first is called the pump start relay. The irrigation controller will send a 24 v signal to the pump start relay telling it to turn on which then sends the power to the second relay, the pump relay. This is where you can save yourself a bit of money in cost of wire. If your motor is 2hp or lower you can buy a motor with the pump relay built into it. If your motor has the pump relay built into it you only have to feed it a 3 conductor pump wire to it. If your motor does not have the pump relay built into it you need to have another stand alone pump relay, and supply the motor with a 4 conductor pump wire. If you are dealing with a long lenth for your pump wire, a 3 conductor wire can save you a considerable amount compared to a 4 conductor wire. Also, have your relays as close to the pump as possible. The reason for this is that standard outdoor 120/240 V wire is considerably cheaper than pump wire. So the less pump wire you use, the more you save.

These are just some of the basics. As far as filtering, and the rest of the installation process make sure you talk to your pump supplier. If your pump supplier won't take the time to teach you, find yourslef another pump supplier. We have a great pump supplier who has taught me a lot of pumps, making my pump installations much better. A properly installed submersible pump is suprisingly low maintenance, but on the other hand a poorly installed one will cause you and your customer a bunch of grief

03-24-2007, 10:03 AM
Thanks guys for replying to my post. I can not place the pump in the water due to the code. So how many of you use a tank with your pump install, would I need one? I am thinking of going with the 1 horse pump. I am figuring about a 4 psi loss for pushing the water up that hill and at 50 PSI I should get about 12.5 GPM then, that sound about right?

03-24-2007, 10:10 AM
Your acting like a homeowner. A 1 horsepower what??? Type is more important than horsepower.

Answer these questions:

Do you intend to water by hand? Wash the car with this water? Or use it strictly for sprinklers?

Do you know what kind of lake strainer your going to use? Some are good some suck.

What size suction pipe are you going to use?

This will help select the right pump.


03-24-2007, 11:18 AM
Tank not essential. Match zones to pump output. Specify the pump a bit more precisely. A cast-iron Goulds J10S shallow-well jet pump would be one example of a 1HP pump you could depend on. Some plastic thingy you get at Home Depot could be a different story.

03-24-2007, 11:56 AM
Boy do I agree with that Boots. 1.5 years is their going average here in my neck of the woods. The same goes for the box store tanks.